"According to the RR engine ping communications, it stayed aloft for 4 hours. Not three, or five, but four. That is pretty exact information.
Actually, that is the most exact information I have seen for quite a while. "
I was under the impression that the pings lasted 4 hours, but that they only occurred every 30 minutes, so that the elapsed time could have been up to 4 hours and 29 minutes.